Ok i got onto yahoo about two weeks ago i was on the first page for me main keyword and sometimes i go search it and its in there and come back later and its not, and then it will be again but today its not and its not even in the search engine my main keyword is my domain so if my when u put these around ur keyword " " and search it my site should pop up if its in the search engine but it doesnt
in the last 2 weeks Yahoo start collecting data from Bing and basically Yahoo had some problems reading data links and things like this, in the last 2 days its look like they start operate OK but you need to take into consideration that this can be happen again in the near future.\
Yahoo has the oldest search database and ranking high on Yahoo is quite a difficult task. Also, since MS and Yahoo are now sharing their search databases due to which there might be some temporary issues with the rankings.
Google is king with huge majority share of searches. My advice.....concentrate more on Google ranking!